The present invention relates generally to fuel cells, and more particularly to fuel cells with films having nanowires therein.
Fuel cells use an electrochemical energy conversion of fuel (including but not limited to hydrogen, propane, methane, carbon monoxide, and the like) and oxidant(s) into electricity and heat. It is anticipated that fuel cells may be able to replace primary and secondary batteries as a portable power supply. In fuel cells, the fuel (usually containing a source of hydrogen) is oxidized typically with a source of oxygen to produce (primarily) water and carbon dioxide. The oxidation reaction at the anode, which liberates electrons, in combination with the reduction reaction at the cathode, which consumes electrons, results in a useful electrical voltage and current through the load.
As such, fuel cells provide a direct current (DC)/voltage that may be used to power motors, lights, electrical appliances, etc. A solid oxide fuel cell (SOFC) is one type of fuel cell that may be useful in portable applications, as well as in many other applications.
Improved thermal characteristics and performance are generally at the forefront of new fuel cell designs. Performance at the anode and the cathode may generally be related to the number of catalytic sites available and the modification of the electronic properties.
In attempts to achieve greater activity and performance at the anode and cathode, porous films and mixed conducting films have been deposited as electrode films, and/or these films have been impregnated.
These films have been deposited by various methods. One such method is physical vapor deposition (PVD). However, maintaining stability of the films in the oxidizing/reducing environment is a challenge. Another method is the glancing angle deposition (GLAD) process. However, GLAD uses an expensive solution, and it is difficult to obtain multi-component metallic/oxide films. Porous films deposited by the above methods generally have a relatively limited number of catalytic sites per unit volume. Mixed conductors (eg. SSCO) also have a relatively limited number of catalytic sites per unit volume.
The impregnation of films with catalysts offers limited control of the shape and size of the particles that strongly affect catalytic activity. Thick film porous anode or cathode supported membranes may be prepared using a press and anneal process. However, this too relatively limits the number of catalytic sites per unit volume.